Electrical heating unit



June 8, 1954 B. AMES 2,680,799

ELECTRICAL HEATING UNIT Filed NOV. 15, 1952 Patented June 8, 1954 UNITEDSTATES OFFICE 3 Claims.

This invention pertains to electrical heating units and more especiallyto a unit for use in cooking apparatus or the like wherein a source ofintense radiant energy is desired. Such a unit is useful, for example,in a cooker of the kind disclosed in the patent to Ames No. 2,581,- 343dated January 8, 1952. While particularly useful in cooking apparatus,the improved unit is also of value as a heat source in other devices,for example in room heaters of the kind disclosed in the patent to AmesNo. 2,555,668 dated June 5, 1951.

Among objects of the invention are to provide a heater unit comprisingimproved means for supporting the heat-emitting resistance coils. Afurther object is to provide an improved heater unit wherein a thin butrigid disk carries spaced brackets for supporting a plurality ofindependent resistance coils in a plane substantially parallel to theface of the disk and spaced from the latter. A further object is toprovide a heater unit wherein a rigid disk or heat-resistant material,for example stainless steel, and which also acts as a reflector,supports insulated resistance coils and carries rigid terminal postsdesigned for telescopic engagement with current-supplying sockets. Otherand further objects and advantages of the invention will be pointed outin the following more detailed description and by reference to theaccompanying drawings wherein:

Fig. l is a plan view of a heater unit embodying the present invention;

Fig. 2 is a bottom view of the unit of Fig. 1;

Fig. 3 is a diametrical section substantially on the line 3-4 of Fig. 1,omitting all but two of the coil-supporting brackets, and to largerscale, showing details of construction;

Fig. 4 is a side elevation, to still larger scale, to one of thecoil-supporting brackets of the unit; and

Fig. 5 is a perspective View of an insulating grommet.

Referring to the drawings, the numeral I designates a supporting plate,here shown as a disk of sheet material. This disk should be rigid andcapable of withstanding the heat radiations to which it is subjectedwithout buckling or oxidizing. Stainless steel is suitable for thepurpose and when of a thickness of the order of TE; inch provides all ofthe requisite stiffness and rigidity. However, while stainless steel iswell suited for this purpose it is contemplated that other materialshaving the proper physical characteristics may be employed. Whatevermaterial is selected should desirably be capable of acting as areflector to reflect heat radiations, which impinge upon it, back towardthe source.

This supporting plate or disk carries a plurality of resistance elementswhich, when traversed by the electric current, admit the desiredradiations. As here illustrated two such resistance elements 2 and 3 areshown, each of these elements consisting of a simple coil of resistanceWire without any interior core, the two resistance elements 2 and 3being arranged so as to form concentric circles lying in the same planespaced from the plane or" the disk l. The terminals li and 3 of theouter coil 3 are connected to terminal posts t and 5 respectively whichpass through openings in the disk 5, with insulation, (Fig. 3) forexample mica washers i3 and l, interposed between the posts and disk,the posts being fixed to the disk in any suitable manner and projectingfrom the opposite side of the disk from that at which the elements 2 and3 are located. Preferably these terminal posts are longitudinally spitand designed for telescopic engagement with current carrying sockets ofconven tional form, thus permitting the disk with the resistance coilsto be installed as a unit in the apparatus of which it is intended tobecome a part and to be removed as a unit merely by pulling the terminalposts out of their sockets. The terminals 8 and 9 of the inner coil 2are connected, one to the post 5 and the other to a third terminal postill similar to the posts t and 5. Desirably the lead ends or" the coils,running from the coils proper to the respective terminal posts, areprotected by suitable insulation, for example a series of insulatingbeads B strung on the lead wires.

The resistance coils 2 and 3 are supported by rigid brackets ll fixed tothe disk 1. As illustrated in Fig. 4, each of these brackets comprisestwo inverted, substantially U-shaped, members desirably formed from astiff metallic wire which is capable of withstanding the heat to whichit is exposed in use. The outer of these two U-shaped members (Fig. l)comprises the parallel legs if: and it united by the substantiallyhorizontal bridging member is, the legs merging with this bridgingmember it at bends 25 and 25 of substantially 96 of arc. The free endsof the legs 32 and iii are screw threaded, as shown at it and it.

The other of the Ushaped members comprises the parallel legs is and 2t!and the bridging mernher 2 l, but this bridgin member is bent to providethe inwardly directed curved portions 23 and 24, these curved portionscooperating with the bends 25 and 26 of the outer U-shaped member toprovide spaces 21 and 23 partially bounded by the inner and outer curves23 and 25 and 24 and 26 respectively. The legs l9 and 21} of the innerU-shaped member are shorter than the legs i2 and E3 of the outerU-shaped member so that when the two members are assembled, as shown atFig. l, with the inner member nested within the outer member and withall four legs lying in the same plane, the lower ends 32 and 33 of thelegs of the inner member are located substantially at the upper ends ofthe screw threaded portions l5 and 16 of the legs l2 and it, while thecentral portion 2i oi the inner U-shaped member contacts the undersideof the bridge member ill of the outer U-shaped member.

Each bracket carries two insulating grommets 29 (Fig. 5) of porcelain orthe like, each grommet having a tubular barrel portion 3%} and radialflanges 31 at its opposite ends.

In assembling the parts, the barrel portions of two grommets are firstplaced within the bends and 26 respectively of the outer U-shapedmember, the inner U-shaped member is then slid upwardly in nestedrelation to the outer U-shaped member until its bends 23 and 2d contactthe barrel 30 of the grommet, and then the parts 2i and M arepermanently united by welding at the point 22. The legs of the inner andouter U-shaped members may also be united by welding, if desired,although this is not usually necessary.

Having prepared brackets as just above described, with their insulatinggrommets 29 clamped in place in the spaces 2? and 28, these brackets arethen mounted on the supporting disk or plate 2! and fixedly securedthereto. For this purpose the disk l is provided with two series ofcircumferentially spaced holes, a hole of the inner series lying in thesame radial plane of the disk as a corresponding one of the otherseries, these holes being of a diameter to permit passage of the screwthreaded ends and iii of the legs i2 and iii of the brackets. The holesof each series are uniformly spaced apart. illustrated there are sixteenof the brackets, but it should be understood that the number of bracketsmay be varied in accordance with the size of the disk and as othercircumstances may warrant.

Each bracket is mounted on the disk with its screw threaded ends l5 andH3 passing through a corresponding pair of holes in the disk and thennuts l'l l8 (Fig. 2) are threaded onto the parts l5 and It at theopposite side of the disk from the resistance coils, thus pulling thebracket downwardly until the ends 32 and 33 of the legs 19 and 28contact the face of the disk, these ends constituting limiting stops.After all of the brackets have been mounted on the disks and their nutstightened, the resistance coils 2 and 3 are threaded. through thebarrels of the grommets, the coil 2 passing through the grommets at theinner corners of the brackets and the coil 3 passing through thegrommets at the outer corners of the brackets, and then the lead ends ofthe coils are connected to the terminal posts,

above described.

With this arrangement the resistance coils are very firmly supported ina definite plane parallel to the disk and in such a way that they do nottend to sag during use. As already noted, these coils are without anycentral core and since they are fully exposed throughout their entirepc- I 'ripheries, intermediate the grommets of adjacent As herebrackets, they are very efiective for emitting intense heat radiations.

Although the resistance coils are thus held very rigidly in position,the entire device is light in weight and easy to handle and readilyinstalled or removed from the apparatus of which it is a part. It shouldalso be noted that because of the mode of mounting the resistance coilsit is a very simple matter to replace one or another of these coils if,after a prolonged period of use it should burn out, since it is notnecessary to remove the brackets from the disk nor to conmeet the coilsto the brackets other than by threading'them through the grommets.

While the brackets are here shown as designed to hold insulatinggrommets for two coils, it is obvious that a single coil may besupported by the same type of bracket, if desired, and it is alsoobvious that by simple modification of the shape of the bracket it maybe possible to support additional resistance coils in the same plane asthe coils 2 and 3.

While a desirable embodiment of the invention has been illustrated byway of example it is to be understood that the invention is broadlyinelusive of any and all modifications falling within the scope of theappended claims.

I claim:

1. In combination in a heating unit, a support, resistance supportingbrackets carried by the support, each of said brackets comprising a pairof approximately U-shaped members each having substantially parallellegs and a bridging portion, the legs of the two members being in the 1eplane, said members being nested one within other with their legs inmutual engagement, the legs of the outer member being longer than andprojecting beyond the legs of the inner member, said projecting endsbeing screw threaded, the bridging portions of the outer and innermembers being so shaped as collectively to form spaced openings, tubularinsulators each having a barrel portion which fits snugly within one ofthe respective openings in the bracket, and means so uniting the innerand outer U-shaped members as firmly to clamp the insulators in place.

2. A heating unit according to claim 1 wherein the support has spacedholes through which the screw threaded ends of the outer U-shapedmembers project, the ends of the inner U-shaped members engaging oneface of the support and constituting stops, and nuts engaging the screwthreaded ends of the legs of the outer members and which engage theopposite face of the support.

3. A heating unit according to claim 1, wherein the bridge pieces of theU-shaped members deviate symmetrically from a point of mutual engagementsubstantially at their .mid length, laterally to the place of mutualengagement of their legs.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,220,781 Parkhurst Mar. 27, 1917 1,480,084 Lamb Jan. 8, 19241,532,104 Lamb et al Mar. 31, 1925 1,539,949 Maclnnes June 2, 19251,563,453 Sutherland Dec. 1, 1925 2,316,222 Butters Apr. 13, 19432,478,808 Deal Aug. 9, 1949 2,567,547 Bussing Sept. 11, 1951

